1. Field of the Invention
The present invention relates to a physiologically active compound HS-1 of the following formula (I) and to a process for preparing the same. The physiologically active compound HS-1 is useful as an antitumor agent or an antimicrobial agent. ##STR2##
2. Description of the Background Art
Chromobacterium violaceum is known as a microorganism producing a purple pigment. This purple pigment is named violacein (Beer, R. J., et al., J. Chem. Soc., 885 (1949); (Beer, R. J., et al., J. Chem. Soc., 755 (1958)) and known to exhibit antimicrobial and antiprotozoal activities. This microorganism which produces violacein is known also to produce some physiologically active compounds other than violacein (HOSHINO, T. et al., Agric. Biol Chem., 54(9), 2339 (1990)).
Antitumor agents which are currently on actual use do not exhibit their activity on carcinoma based on distinct differences between cancer cells and normal cells, but identify cancer cells based on their vigorous division and growth activities, the capability of attracting substances, or the insufficient metabolizing activity. Selective toxicity actions of the conventional antitumor agents are therefore reduced on cancer cells which grow slowly. Because of this reason, most antitumor agents currently on use accompany serious side effects such as toxicity to heart, alopecia, gingivostomatitis, leukopenia, and gastrointestinal injury. The conventional antitumor agents have also a problem of drug tolerance. Therefore, there has been a desire for the development of a compound which can exhibit an antitumor activity based on a mechanism different from those in conventional antitumor agents.
The present inventors have undertaken screening of various compounds produced by Chromobacterium violaceum which is the violacein-producing microorganism, and, among compounds produced by Chromobacterium violaceum in the presence of tryptophan, discovered a novel compound HS-1, having the chemical structure represented by the formula (I) below and exhibiting toxicity against cancer cells.